Cigarette



June 13, 1961 M. o. scHuR 2,988,088

CIGARETTE Filed Aug. 10, 1954 INVEN TOR.

MILTCN O. SCHUR (Law. 21/.

AGENT United States Patent C CIGARE'I'IE Milton 0. Schur, Asheville, NC, assignor, by mesne assignments, to Olin Mathieson Chemical Corporation,

a corporation of Virginia Filed Aug. 10, 1954, Ser. No. 448,815 2 Claims. (Cl. 131-40) This invention relates generally to cigarettes and more particularly to an improved cigarette having a filter stub or tip for the tobacco smoke.

It has been proposed heretofore to provide cigarettes with a stub of absorbent paper, cotton or other filtering medium to remove undesired constituents from the tobacco smoke. Such filters reduce the tar and nicotine content of the smoke a substantial extent by mechanically retaining some of the particulates entrained in the smoke. Some, if not all, of these filters, however, remove very little, if any of the gaseous constituents of the smoke including acrolein, hydrocyanic acid, carbon monoxide and other highly objectionable substances. Furthermore, in order to be sufficiently efiective to warrant their use, it has been necessary that the construction of most of the filters be such that they offer substantially more resistance to the fiow of air and smoke therethrough than would a comparable length of conventional cigarette tobacco compressed to the density of the average cigarette. Expressed in common parlance, the filter noticeably increases the drag or draw on the cigarette when the smoker pulls a normal volume of air and smoke into his mouth during a puff. Consequently, the heretofore available filter tip cigarettes have not been entirely satisfactory because many smokers object to a cigarette which has a noticeably increased resistance or drag to the flow of smoke therethrough. It has been proposed, heretofore, to perforate the wrapper of a conventional cigarette not having a filter tip in order to decrease the draft resistance of the cigarette but such cigarettes have the disadvantage of imposing too little resistance to the flow of smoke to be acceptable to the average smoker.

It is therefore an object of this invention to improve the smoking characteristics of cigarettes having a filter tip. Another object of this invention is to provide a means for reducing the quantity of harmful gaseous components, including acrolein, of the cigarette smoke as well as reducing the particulate constituents thereof before the smoke is delivered to the mouth of the smoker as the cigarette is consumed without seriously impairing the smoking characteristics of the cigarette. Still another object of this invention is to provide a cigarette having an effective filter tip which imposes a resistance to gas fiow in the neighborhood of the resistance of a conventional cigarette not having a filter tip. A further object is to provide a filter tipped cigarette having improved taste characteristics. A more specific object of this invention is to provide a cigarette having a filter tip which has smoking characteristics comparable to the conventional cigarette not having a filter tip and which is capable of delivering smoke which contains less than the normal concentration of all components of cigarette smoke.

The foregoing objects, as well as others, will become apparent from the following description in conjunction with the accompanying drawing, in which FIGURE 1 is a perspective view partially in section of one embodiment of this invention;

FIGURE 2 is a perspective view partially in section of another embodiment of this invention; and

FIGURE 3 illustrates in a perspective view, also partially in section, a third embodiment of this invention.

Generally speaking, the objects of this invention are Patented June 13, 1961 attained by combining in a cigarette a filter tip and a means for admitting sufficient air into the cigarette adjacent the month end thereof to dilute the smoke by at least about 20 percent. In accordance with one form of the invention, a series of orifices of predetermined number and size are provided in the wall of the cigarette and they may be located either in the cigarette wrapper which encloses the tobacco column adjacent the filter tip, or they may be located in the region of the filter tip or in a mouth piece attached to the filter tip. In another form of the invention a cigarette wrapper having a zone of a substantially greater porosity in the region of the filter tip than in the remainder thereof is utilized. For example, the wrapper may be of a composite structure, the portion in the region of the filter tip having a substantially open structure similar to conventional stencil tissue while the remainder of the wrapper is conventional cigarette wrapping paper.

This invention is predicated upon the discovery that the smoke passing into a smokers mouth from a filter tipped cigarette can be attenuated, Without detrimentally affecting the taste of the tobacco smoke, so as to compensate for the difference between the resistance of the filter tip to the passage of smoke therethrough and the resistance imposed by a tobacco column of similar length. Indeed, in most instances the taste of the smoke of the filter tipped cigarette is improved. In contradistinction, the reaction of the smoker of an ordinary untipped cigarette is unfavorably affected if the wrapper is perforated. The size and number of the orifices in the filter tipped cigarette wall or the porosity of the zone adjacent the filter tip which gives optimum results will vary with the type of filter utilized, but for the best results, insofar as taste and improvement in smoking characteristics such as improvement in draw of the cigarette, is concerned, the porosity can be such as to result in the dilution of the smoke by at least about 20 percent. The invention thus provides a means for greatly reducing the concentration of the various components of the tobacco smoke by combining a means for attenuating or diluting the smoke with air and additionally filtering the smoke to absorb and adsorb constituents therefrom.

The filter tip or stub can be composed of any absorbent material with or without adsorbents included therein but it is preferred that one of the more effective absorbent paper filter tips be utilized. Any material capable of adsorbing components from the tobacco smoke or reacting therewith such as, for example, activated charcoal, cuprous chloride, aluminum hydroxide or the like may be utilized. It is preferred, however, to use a combination of the porous zone provided by this invention and the filter tip disclosed in the co-pending application of Milton 0. Schur and James C. Rickards, Serial Number 400,072, now abandoned, filed December 23, 1953, or the filter tip of co-pending application of Milton 0. Schur, filed July 13, 1954, now US. Patent 2,915,069, issued December 1, 1959, or the filter tip described in the co-pending application of Milton 0. Schur, filed July 13, 1954, SN. 442,978, now abandoned. These filters are particularly advantageous for removing both particulate and some gaseous components from the tobacco smoke but it has been found that by combining these filters with a means for attenuating the smoke the quantity of acrolein and other adsorbable gas components in tobacco smoke can be even further reduced and that this additional reduction is achieved without seriously altering the drag imposed by the cigarette to the flow of smoke and without seriously impairing the taste of the smoke or otherwise deleteriously affecting the smoking char: acteristics of the cigarette. Indeed, as pointed out else where herein, the taste is improved. Maximum quantities of acrolein are removed if the filter combined with 3 the porous zone in the cigarette wrapper contains particles of activated charcoal. In order that the objectives of this invention are achieved, it is essential that the cigarette have a filter tip or similar restriction at the mouth end thereof which imposes a greater resistance to the flow of smoke therethrough than would a similarly dimensioned column of tobacco of the density ordinarily utilized in cigarettes.

In the drawing, FIGURE 1 illustrates one embodiment of this invention in which cigarette 1 is composed of wrapper 2 enclosing tobacco 6 and filter tip 3. Wrapper 2 is provided with a series of orifices '4 having a total area such that sufiicient air enters therethrough to compensate for the difference between the resistance to the flow of smoke imposed by the filter 3 and the resistance of a comparable length of tobacco 6. Preferably, filter 3 is formed in accordance with the method disclosed in the copending application Serial Number 400,072, referred to hereinbefore. Such a filter tip ordinarily imposes a resistance to the flow of smoke equivalent to a column of water 32 millimeters high when the flow through the tip is 17.5 cc. per second. The series of orifices =4 admit sufiicient air into the cigarette to compensate for the difference between this resistance of the filter tip and the resistance imposed by a similar length, for example, 13 centimeters, of conventional cigarette tobacco compressed to the density of the average cigarette.

In FIGURE 2, a cigarette 1 containing tobacco 6 and filter 3, similar to that of FIGURE 1, enclosed in wrap- 'per 2 is shown with a firm paper mouth piece 5. In this embodiment the series of orifices 4 having a diameter similar to that of the foregoing embodiment are provided in the mouth piece in such a position that they will not become covered by the lips of the smoker.

In the embodiment illustrated in FIGURE 3, cigarette 1 containing tobacco 6 and filter 3 has been provided with a series of orifices 4 extending through wrapper 2 adjacent the filter. In this embodiment the air passes directly into a filter tip 3 and is injected into the various passageways therethrough to compensate for the resistance imposed by the filter tip to the flow of smoke to such an extent that the cigarette can be smoked as easily as the conventional cigarette not having a filter tip.

It is fundamental to this invention that through a choice of predetermined number and size of orifices 4, illustrated in the various embodiments of the drawing, the drag required to pull a given volume of air and smoke through the filter tip can be adjusted to be equivalent to the drag required to pull an equal volume of smoke through a conventional cigarette not having a filter tip. This is accomplished by providing the orifices 4 which introduce a second path, in parallel with the path through the rod of tobacco 6, for air to enter the cigarette adjacent its mouth end. Through control of the size and number of orifices 4, the resistance to flow in the cigarette 1 is decreased to the extent that the filter 3 would increase the over-all resistance of the cigarette had not the wrapper been perforated.

Ordinarily, in practicing this invention, it is preferred that'the resistance of the filter tipped cigarette be adjusted within a range such that it does not deviate by more than about 30 percent from the resistance of the conventional cigarette. By way of example of the accomplishrnents of this invention, if the size of the orifices 4 provided in the wrapper of any one of the embodiments thereof is preselected so that the resistance of the orifices is equal to the average resistance of a rod of tobacco 6 during the smoking of the cigarette, the volume of smoke drawn through the rod of tobacco 6 from the burning zone of the cigarette during a normal pull will average approximately one-half that of the smoke pulled through the conventional cigarette. This alone lowers the concentration and the amount of smoke passing through the cigarette by about one-half that which would pass through an ordinary cigarette. But if the filter retains any of the constituents in the smoke the total reduction in the concentration of the various constituents passing through the filter will be proportionately less. For example, if we assume that 30 percent of the particulates in the smoke are retained by the filter, the total reduction in the concentration and amount of particulates passing through the filter would be about 65%.

In the above example, if the average drag on the cigarette is to be normal, the conductance of the filter tip 3 would manifestly have to be equal to that of the sum of the average conductance of the tobacco rod 6 and the conductance of the orifices 4. Filter tips in common use with a conductance of this order will retain only about 30% of the particulates in the smoke. Such tips during a normal puff increase the drag on a conventional cigarette during a normal pufi by more than about 40% Further, they remove or retain no significant quantities of the constituents of the gas phase of the smoke. In contrast, the cigarette of the present invention, carrying a similar filter tip, but provided with the orifices of the example given above, delivers to the smoker during each normal pufi only about 50% as much of the gaseous constituents of the smoke as he would receive from a conventional cigarette without a filter tip. The resistance of the lighted cigarette having the combination of a filter tip and orifices in the cigarette wrapper adjacent the filter is equivalent to a column of water about 70 mm. high which is substantially the same resistance as that of the average lighted ordinary commercially available cigarette not having a filter tip.

It is apparent from the foregoing that the cigarette provided by this invention provides a means for attenuating the particulate as well as the gaseous constituents of tobacco smoke and that moreover this objective is accomplished without materially increasing or decreasing the resistance of the cigarette to the flow of gases therethrough. That is, a cigarette having improved smoking characteristics, insofar as taste and reduction of harmful constituents in the smoke is concerned, is provided without at the same time introducing an undesirable characteristic. Although the resistance of the filter tip at the month end of the cigarette will vary over a wide range, depending upon the construction of the filter tip used, it is seldom necessary to use a filter which imposes a resistance to the flow of gases therethrough greater than about 5 times the resistance of a column of cigarette tobacco of equal'length and compressed to the same extent as tobacco is compressed in a cigarette. It is preferred that the resistance of the filter tip or restriction be about 25 percent to about 75 percent that of the resistance of the original, untipped, unperforated cigarette when first lighted. For best results, it is preferred that the resistance of the filter tipped cigarette to the flow of smoke therethrough not deviate more than about 30 percent from the resistance of typical untipped cigarette.

The resistance imposed by a filter of a given construction has been found to vary only a slightly extentfrom one filter stub to another. It is, therefore, possible to determine by experiment the average resistance imposed by a filter of a particular construction and then to perforate the wrapper while the cigarette is in the testing apparatus until the resistance to the flow of smoke is reduced to the desired resistance. After the proper size and number of orifices has thus been determined, similar perforations can then be placed in cigarettes as they are manufactured to provide cigarettes embodying this invention. As indicated hereinbefore the desired resistance is substantially equal to that of a commercially available cigarette not having a filter tipor, in other words,-in typical cigarettes equivalent to a column of water about 70 mm. high when gas is flowing through the lighted cigarette at the rate of 17 /2 cc. per second.

If it is desired that less of the particulates be filtered out for a given attenuation of the constituents of the gas phase, a less efiective filter tip is used on the cigarette of the present invention. By way of example, this can be accomplished Without lowering the resistance to flow through the tip it the filter is comprised of crumpled tissue paper prepared from highly beaten pulp. As the retentivity of the stub for particulates approaches zero, and the stub thereby becomes no more than a restriction, the extent of the reduction in concentration of the particulates in the smoke manifestly approaches that of the gas phase until, in the limit, they become equal.

Typical test data which illustrates the difference between the conventional cigarette and those of the present invention are as follows:

Experiment 1 Conventional untipped cigarettes 70 millimeters long by 26 mm. in circumference, weighing on the average 1.00 gram each, and having after being lighted a drag equivalent to a column of water 70 mm. high when the flow of air and smoke through the cigarette is 17.5 cubic centimeters per second, were smoked in a smoking machine which takes a 2 second puff once a minute, each putt pulling 35 cc. of air and smoke through the cigarette into a smoke collector. After a 47 mm. length of cigarette has been consumed, the cigarettes were discarded. On the average, 9.5 puifs per cigarette were required. The smoke thus collected was carefully dissolved in a solvent consisting of 3 parts of ethyl alcohol and 2 parts of toluol by volume, the solution transferred to a weighing bottle, the solvent evaporated at room temperature, the residue heated overnight at 95 C., and weighed. The residue amounted to 25.6 milligrams per cigarette.

Other cigarettes from the same carton were similarly smoked and the gas phase of the smoke analyzed for acrolein. It was found that on the average a total of 0.025 mgm. of acrolein per cigarette passed into the collector.

Experiment 2 To similar cigarettes were aflixed filters formed in accordance with the method disclosed in the co-pending application of Milton 0. Schur and James C. Rickards filed December 23, 1953, and comprised of crumpled tissue paper prepared from cellulose fibers only slightly beaten prior to the formation of the sheet. The filter was 13 mm. long. To keep the over-all length of the filter-tipped cigarette the same as that of the original cigarette, a 13 mm. length of the tobacco rod was cut oif the free end of the cigarette before the filter-tipped cigarette was smoked in the smoking machine. Laboratory measurements showed that in order to suck 17.5 cc. of air and smoke per second through the lighted filtertipped cigarette with an over-all length of 70 mm., a drag or suction equivalent to a column of water 86 mm. high now had to be applied. As in the case of the untipped cigarettes of Experiment 1, an average of 9.5 puffs were required per cigarette to reduce the length of the cigarette by 47 mm.

The weight of smoke collected averaged 16.3 mgms. per cigarette. The weight of acrolein found in the smoke passing into the smoke collector averaged 0.025 mgm.

Thus, the filter tip removed 36% of the particulates and none of the gaseous acrolein.

Experiment 3 Another set of these filter-tipped cigarettes was then prepared, but in this case, tiny holes were pricked through the cigarette wrapper near the juncture of the filter and the tobacco rod, as indicated in FIGURE 1. The size of the holes were such that the drag necessary to pull 17.5 cc. per second of air and smoke through the tip at the start of smoking was equivalent to a column of water 70 mm. high. On the average, 10.1 puffs were now required to consume the same length of tobacco rod as in the previous experiment. Each of the cigarettes was found to deposit on the average 10.8 mgms. of smoke in the smoke collector; the weight of acrolein found passing into the collector averaged 0.018 mgm. per cigarette;

It is thus seen that the orifices pricked through the cigarette wrapper not only reduced the drag of the filtertipped cigarettes from an initial value of 86 mm. down to 70 mm., i.e., to that of the untipped cigarette of Experiment 1, but lowered the particulates passing into the collector 58%, as compared with the untipped cigarette, and the amount of acrolein by 28%.

Experiment 4 In another experiment, the filter was comprised of tissue prepared from highly beaten cellulose fibers. Its resistance to the flow of air and smoke was the same as in Experiment 2. In the present experiment, the filter tip removed only 15% of the particulates from the smoke, and since there were no by-pass holes pricked through the wrapper, the quantity of acrolein in the smoke was the same as in the case of an untipped cigarette.

Experiment 5 When, however, cigarettes such as those used in Experiment 4 were provided with the tiny orifices so as to bring the drag back to that of an untipped cigarette, the weight of particulates passing into the smoke collector was 42% less than in the case of the untipped cigarette, and the weight of acrolein was reduced by 32%.

Experiment 6 In Experiment 6, a filter tip of the same resistance as in Experiment 2 was used. It was comprised of paper made from pulp beaten to an intermediate extent and containing 4.7% of activated charcoal. The weight ofparticulates entering the smoke collector was found to be 21% less than that of the untipped cigarette of Experiment 1;but because of the presence of activated charcoal in the filter tip, the quantity of acrolein in the smoke was less by 26%.

Experiment 7 When the filter tip such as that used in Experiment 6 was provided with tiny orifices in the cigarette wrapper to bring the drag back to that of an untipped cigarette, the weight of particulates passing into the smoke collector was found to be reduced by 54% as compared with the untipped cigarette, and the Weight of acrolein by 48%.

It becomes apparent from the foregoing that the extents to which the particulate phase and the gaseous phase of the smoke can be reduced in concentration and in total amount entering the smokers mouth is controllably variable over a wide range by the cigarette manufacturer through the selection of various appropriate combinations of filter tip resistances, filter capacities, and by-pass orifice resistances.

In order to clarify the invention further and to facilitate application thereof, following is a. postulation of an example utilizing the principles believed to be involved, which necessitates the following assumptions and approxima-tion:

(1) The pressure drop through an untipped, unlighted cigarette 7 0 mm. long at a flow of air or smoke through it equal to 17.5 cc. per second is equivalent to a column of water 51 mm; through a lighted cigarette, the pres-' sure drop is equivalent to a column of water 70 mm. high.

(2) The pressure drop through an unlighted cigarette is proportional to its length.

(3) The over-all length of the cigarette, i.e., the rod masses (7') During-the pufiing, is drawn into the 'smokers mouthzatth'era'te.o'f 17.5 cc. persecond.

'In the equations Ibe'low, resistance to flow of air and smokeis expressed numerically as the'suction, in mm. of water, required to pull air and smoke at the rate of 17.5 cc. per second through the rod of tobacco, filter tip, bypass orifices, 'or over-all cigarette.

Let:

R=resistance of the burning tip of the cigarette to the flow of air and smoke.

R"=resistance of the non-burning portion of the rod of tobacco.

R =resistance of the rod of tobacco including burning tip.

R =the resistance of the orifices in the cigarette wrapper in the region of the filter Itip.

R =resistance of the filter tip.

R=resistance of R and R which are in parallel.

L=length of the column of tobacco in millimeters.

N=number of puffs necessary to consume a 47 mm.

length of the tobacco rod. =cc. flow of air through the by-pass openings in the region of the filter tip.

F =cc. flow of air and smoke through the tobacco rod per second.

(3) R=70R,=70-32=38, when L==59 mm.

NOW o/ o o/ 01 made above.

(7) when L==59 mm., /17.5

according to assumptions +19=26+19=45, and

+19=8.8+19=27.8, and

L, mm. F.,/17'.5, percent Average value of F./17.5=69%.

If "the "filter, :as in Experiment 2, described above, is capable of retaining 36% of the particulates, by weight, then the combined effect of such retention and of the diluting effect of the air entering the by-pass orifices for the case under calculation should reduce the amount of particulates entering the smoke collector by When a typical domestic cigarette such as was used in Experiment 1, described above, is smoked in the smoking machine, it is found that 9.5 cycles, counting from the start of the first puif, are required, on the average, to consume the cigarette from an initial length of 70 mm. to a butt length of 23 mm, i.e. to consume (704.3) or 47 mm. of tobacco rod. This length weighs, 0n the average,

or 671 mg. Since each puif is of 2 seconds duration, and since a .cycle extends from the start of one putt to the start of the next putf, the total time of puffing=9.5 2 or 19 seconds; and since a cycle starts every 60 seconds, the total time between puffs averages per cigarette (9.51) (60-2) or 493 seconds. As stated previously, measurement shows that a typical cigarette burns at the rate of 47 mg. per minute between pufis. Hence, during the smoking of the cigarette in the smoking machine or 386 mg. of tobacco burns between puffs, i.e., the smoke from 386 mg. of tobacco escapes into the air, while that from (671-386) or 285 mg. leaves the rod of tobacco at the month end. This is manifestly equivalent to or -310mg. tobacco .per pulf.

The assumption may be made, suitable for our present purpose, that the weight of tobacco consumed during a putt, is proportional to the quantity of air drawn through the rod of tobacco, within the limits of variation covered by the cases under consideration. Expressed otherwise, the weight of tobacco consumed during a puff a 30( )n1g.

Since, in'the tipped and perforated cigarette under consideration, the average calculated value of the average Weight of tobacco consumed during a puft' If N=the number of puffs required to consume 47 mm. of tobacco rod,

smoke emerging from the mouth end of the cigarette was about 30% less from the cigarette of Experiment 3 than would be true if a conventional cigarette, as the cigarette in Experiment 1, was utilized. Moreover, the particulate components of the tobacco smoke were reduced about 58%. Such results are far superior to any results heretofore obtained by merely filtering the tobacco smoke. Comparison of the results of Experiment 7 with the results of the other experiments recorded herein illustrates the advantage of combining a filter containing activated charcoal with a means for attenuating the smoke of a burning cigarette.

Although various embodiments have been described in detail in the foregoing for the purpose of illustration many modifications will occur to those skilled in the art and can be made without departing from the scope of the invention except as is limited by the appended claims.

What is claimed is:

1. A cigarette comprising a unitary outer wrapper for enveloping its contents and defining the body portion thereof, said wrapper having therein a section of tobacco of constant length, and a mouth-end section comprising a separable non-tobacco filter, said latter section being distinct from said first section by a clearly defined peripheral line of perforations on the surface of the said wrapper, said wrapper extending the full length of the tobacco section and filter section.

2. A filter tip cigarette eficctive to reduce the particulate components and the undesirable gaseous components, normally inhaled by a smoker, by as much as 50% and 30% respectively below the amounts inhaled from a conventional cigarette, said cigarette being further characterized by having a filter whose resistance to draw is substantially greater than the resistance offered by a column of tobacco of length equal to the length of the filter comprising: in combination a column of tobacco, a combustible wrapper therefor, and a filter abutting one end of said column, said wrapper being provided with a plurality of spaced openings, said filter and said openings being so constructed and so arranged to operate to reduce the initial resistance to draw of the filter tip cigarette to a level of not more than about 25% greater than the initial resistance of said conventional cigarette.

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